Aspirin, a Wonder Drug? Studies Show It May Prevent Cancer

Many people take a daily aspirin to reduce their risk of heart attack, but now fresh evidence suggests that the over-the-counter pain reliever may be a powerful tool in cancer prevention as well.

In three new studies published in the Lancet,
researchers from from the University of Oxford say a daily dose of aspirin can reduce people’s risk of developing a variety of cancers and also lower the chance of their cancer spreading.

The studies looked at patients who were participating in several long-term, randomized trials on the effect of daily low-dose aspirin (75 mg to 300 mg) for the prevention of heart disease. The researchers examined how many of the participants went on to develop cancer. In one study, patients taking aspirin had a nearly 25% lower risk of cancer after five years, compared with those taking a placebo. That translated to a 15% lower risk of dying of cancer during the study period; after five years, the risk of death was 37% lower in patients who remained on aspirin.

In another study, which included five large trials in Britain that followed patients over an average of 6.5 years, aspirin users enjoyed a 36% lower risk of developing metastatic cancer and a 46% reduced risk of being diagnosed with colon, lung or prostate cancer.

A third study, published in Lancet Oncology, looked at findings from observational studies and found that regular use of aspirin reduced the long-term risk of several cancers and prevented the metastasis of tumors.

Taken together, the findings are the first to show the benefits of aspirin in lowering cancer risk in short periods of time. Earlier studies had demonstrated reduced risk after about 8, 10 or as long as 20 years.

“These findings add to the case for use of aspirin to prevent cancer, particularly if people are at increased risk,” lead researcher Dr. Peter M. Rothwell, a professor of neurology at the University of Oxford, told Reuters.

The benefits of the low-cost therapy have to be balanced with its risks, however, which include gastrointestinal bleeding. Over time, said Rothwell, the risk of such bleeding appeared to wane, but additional studies need to be done to confirm that the prevention of cancer outweighs any potential complications that might arise from aspirin’s effect on the stomach.

That type of evidence is what some experts are still waiting for. “I think he’s on to something. I just want to be cautious, and I don’t want to exaggerate,” Dr. Otis W. Brawley, chief medical officer and executive vice president of the American Cancer Society, told the New York Times. “I’m not ready to say that everybody ought to take a baby aspirin a day to prevent cancer.”

Still, the idea that an inexpensive and relatively safe medication can prevent a range of cancers is powerful, and the results should launch a deeper look into aspirin’s potential chemoprotective effects. Whether such trials will be undertaken is another matter, considering the expense of clinical trials and the lack of profitability of generic, over-the-counter aspirin.

Alice Park is a writer at TIME. Find her on Twitter at @aliceparkny. You can also continue the discussion on TIME’s Facebook page and on Twitter at @TIME.